Method and machine for grinding chasers



im 8 1 LE. FLANDERS METHOD AND MACHINE FOR GRINDING C'HASER'S April 18, 1933. 1,904,304

R. E. FLANDERS METHOD AND MACHINE FOR GRINI JING CHASERS Criginal Filed Jung 15, 192s s Sheets-Sheet 2 Aiml 1933' V R.,. E. FLANDERS METHOD AND MACHINE FOR GRINDING CHASERS 3 Sheets-Sheet 3' Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE I RALPH E. FLANDEBS, OE SPRINGFIELD, VERMONT, AssIeNoR r .IONEs & LAMSON MACHINE COMPANY, or sPRINGEIELn, VERMONT, A CORPORATION or VERMONT METHOD AND MACHINE FOR GRINDING CHASERS Application flledj'une' 15, 1923, Serial No. 645,516. Renewed November 18, 1930.

tending outwardly in radial directions and the mandrel rotated in contact with the face of a grinding wheel of the proper cross section to form the threads, the chaser threads will be formed convex, the degree of convexity depending on the diameter of the mandrel, the smaller this diameter the greater being the degree of convexity. In actual use these chasers face inwardly so that for proper engagement with the work their thread I faces should be concave rather than convex.

This invention, therefore, provides a method and machine by which the thread faces maybe ground concave and yet the chasers by supported for presentation to the grinding wheel on a mandrel with t e thread faces presented outwardly and a ran ed circumferentially relative to the man rel so that several chasers may be presented successively to the Wheel. This is. accomplished by effecting a relative bodily movement of the mandrel and grinding wheel toward and from each other to efl'ect the grinding of the threads only when the chaser is directed substantially toward the wheel and during such a short period relative to the speed of rotation of the mandrel that it has. substantially no angular motion relative to the wheel. At other times the chaser is out of contactwith:

the wheel. The radius of the grinding wheel, therefore, determines the maximum concavity which can be produced, the smaller the wheel the greater beingthe concavity since I out the method of this invention.

F gure 2 is an end elevation of aborti thereof.

which, as shown, is fixed in a collar 4 made Figures 3 and 4. are fragmentary sectionson lines 3-3 and 4-4, respectively, of Figure 2, Figure 3 corresponding to a portion of Figure 1 but on a larger scale.

Figure 5 is a side elevation of a chaser supporting mandrel.

Figure6 is an end view of the same.

- Figure 7 is a framentary section on line 77 of Figure 6.

Figure 8 is a view similar to a ortion of Figure 5 but illustrating a modi cation.

Figure 9 isa diagrammatic development of the chasers as arranged on the mandrel.

Referring first to Figures 5 to 9 illustrating the mandrel for supporting the chasers, it will beseen that this mandrel comprises a shank piece 1 having a disk shaped head'2 at one end thereof and its other end having at tached thereto a radially extending arm 3 '30 fast to the end of the mandrel, this arm being positioned for engagement with any suitable form of lathe dog by which rotation of the' mandrel may be effected. The head 2 is provided with a series of recesses 5 extending inwardly from the end face thereof, each recess being shaped to receive the chaser shown at 6 with .its threaded portion 7 projecting substantially radially outwardly. An annular plate 9 overlies the inner end of each recess, being firmly seated in a counterbored portion 9a of the head. The inner ends of the chasers underlie this plate and a shoulder 7a of each chaser abuts its outer edge. The chasers may be held clamped in position by clamping plates 10, each plate bridging a pair of adjacent chasers and the edge of the plate 9, and being urged against the chasers or released therefrom by manipulation of screws 11 passing therethrough between the chasers and threaded into the head 2. Axially of the mandrel and extending from the outer face of the head 2 is a concentric portion12 centrally bored at its end as at 13 for the reception of a 9; tailstock of the grinding machine as will later appear. Normally four chasers constitute,

a set and as herein shown a pair of sets, comprising eight chasers, may be supported by the mandrel at one time. These chasers mhst be so related when in position on the mandrel that the grinding wheel may mate the threads of successive chasers as they are presented thereto by the rotation of the mandrel, that is, the chasers must be so positioned relatively endwise that the grinding wheel will pass from proper mating relation with the threads of one chaser to proper mating relation to the threads of the adjacent chaser. This may be accomplished by relatively offsetting the chasers of one set relatively to the chasers of the other axially of the mandrel as indicated in Figure 9. The chasers of each set are positioned alternately, that is, the chasers a, b, c and (1 form one set and the chasers a, b, c, d form the corresponding chasers of the other set. As there must be relative motion between the grinding wheel and the chasers axially of the wheel conforming to the pitch of the threads, it is necessary that a relative axial motion be given the mandrel and the wheel as the mandrel rotates. As the threads in the chaser a are in the same relative position as the threads in the chaser 26 a, but as they are in different angular positions on the. mandrel, it is therefore necessary to offset the chaser afaxially of the mandrel a distance corresponding to itsangular spacing from the chaser a and as shown this spacing being one-eighth of the circumference of the mandrel the chaser a must be offset one-eighth of the pitch of the threads being ground. This is shown diagrammatically in Figure 9 wherein the line a:y represents the pitch line of the threads, the

chaser a bein laterally offset from the chaser a so that it correctly mates the wheel as the mandrel is turned one-eighth of its revolution. The threads of the chaser b are, of course, one-quarter of the pitch of the threads laterally offset from the threads of the chaser a, since they must form a continuation of the threads thereof when assembled to cooperate therewith. The chaser I), therefore, is positioned the same as the chaser a in the mandrel since it is positioned in the 'mandrel 90 from the chaser a which is the working angle thereto. Likewise. the chasers c and d are also ositioned in the same manner. Since the chasers b, e and d have the same relation to the chasers b, 0, and d that the chaser a has to the chaser a, it is necessary to offset them in the same manner as the chaser a.

As the angle to the axis of a threaded member for any particular lead varies with the size of the member and as the size of the chaser threads when in operative inwardly facing position is much smaller than when chasers angularly disposed with reference to the axis of the mandrel, as is shown in Figure 8,or by inclining the axis of the grindseated in sockets parallel to the axis of the mandrel so that with this form of mandrel the wheel is given an inclination equal to the helix angle of the thread to be cut by the chaser. When the sockets are set at an angle, which should be the algebraic sum or difierence (depending on whether right or left hand threads are being ground) of the helix angle on the work and the helix angle of the chasers as mounted in the mandrel when given their proper lead or advance feed, the wheel is set to the proper helix angle for the lead of the chasers as mounted in the mandrel.

As before noted, in order that the thread surfaces of the chasers may be ground con cave, each chaser is presented to the wheel while substantially stationary angular-1y and in order to accomplish this, the machineillustrated in Figures 1 to 4 has been designed. This machine maybe of the type illustrated in my Patent No. 1,739,753, granted December '17, 1929 for grinding machines, to which reference may be had for an understanding of many desirable features not necessary to a complete ,disclosure of the present invention. Referring to Figure 1 it will be noted thatthis ,machine comprises a base 20 on which is supported a traversing carriage 21 which is designed to carry the mandrel and to rotate and traverse it relative to any suitable form of grinding wheel, which is preferably adjustable about an axis transverse to the axis of rotation of the mandrel in order to permit its angular presentation to the work 0 be adjusted. Such a wheel is shown in dotted lines at 22 in its vertical position and at 22 in a position adjusted at an angle to the vertical. The carriage 21 has a headstock 25 and a tailstock 26. The headstock 25 carries a spindle 27 which projects through a sleeve 28 axially adjustable within a bearing 29 of the headstock. The inner end of this sleeve has journaled thereon a face plate 29 having an arm or dog 30 projecting therefrom in position to engage the arm 3 extending radially from the mandrel, the mandrel being supported between the spindle 27 and a spindle 35 of the tailstock.

The face plate is rotated to rotate the mandrel by means of a shaft 40 journaled in a sleeve 41 movable with the sleeve 27 and slidable through a portion of the bearing 29. It is also journaled in a sleeve 42 also slidable through this bearing. Between 7 these sleeves the shaft has fixed thereto a gear 43 which meshes with a long gear 44 on a shaft 45 journaled longitudinally in the carriage 21. The inner end of the shaft carries a gear 46'meshing with teethcut in 5 the outer face of the face plate so that by rotation of the shaft the face plate is I caused to rotate and by it the mandrel is given, its rotary motion in time with the rotation of the shaft 45. The shaft 45 has fixed thereon a long gear 50 with which meshes a pinion 51 on a stub shaft 52 fixed in the base portion 20 of the machine. As shown this gear 51 in turn meshes with a gear 53 keyed to a shaft 54 and on this shaft is journaled a gear 55 having formed in one face thereof clutch elements 56 with which may be brought into mesh mating faces 57 on a clutch collar 58v slidable axially of the shaft. The gear. 55 is'driven by a pinion 59 fixed to a shaft 60 to which shaft is also fixed a gear 61 with which meshes apinion 62 on a main drive shaft 63. This drive shaft extends outwardly of the machine frame and has fixed thereto'a driving member such as a belt wheel 64. The shaft 54 above referred to also extends outwardly of the -machine frame and has fixed thereto a gear 65 which 'meshes with a'gear 66 carried by a shaft 67. This shaft 67 has at its other end a worm 68 fixed thereto which meshes with a worm wheel 69 fixed to or forming part of a cam drum 70; the function of which will later' appear. Y

The shaft'45 carried by the traversing ear of the tailstock spindle 35 in order to effect presenting and withdrawing act on of the chasers carried by the mandrel relative to the grinding wheel.

spindle 35. The spindle 35 is supportedtherein with capability of a pivotal motion. For th s purpose the inner end of this sleeve is formed with a flange .75 to which may be fixed a flange 76 of a collar 77. This collar is formed with a bearing block 78 shaped to rockably receive. a spherical segmental block 79 through which the spindle 35 passes and to which it may be fixed. These blocks are supported in' matin position by means of a retain ng collar 80 tfireaded over the extrem ity of the collar 77 and having an :inwardly directed annular flange 81 overlying the seg- 1 mental bearing block.

The rear end of the spindle 35, as shown best in Figure 3, extends loosely through a sleeve 83 fitted within the sleeve 7 3, thesleeVe 83 having a. retaining collar 84 at its outer end between which and the end of the sleeve 65 73 is pivoted on the sleeve 83 a plate 85. This riage is also caused to'eifect-a pivotal motion- For this purpose the shaft 45 has a reduced extremity 7 0' on which the cam arm 87, therefore. it is evident that the rear'end of the spindle" maybe moved bodily about the pin 86 as a center. Such motion of the outer end of the spindle causes a similar reversed motion of less amplitude to the inner end of the spindle which engages the chaser supporting mandrel. By rocking I this cam arm, therefore, the mandrel may be caused to approach and recede from the grinding wheel. Th s is done in time with its .rotation so that when a chaser is presented in proper position it is given a quick m'o tion toward the wheel to effect a grinding action thereon and is then retracted, this act on ta 'ng place during such a small period of time that the angular position of the chaser is substantially constant, the chaser being removed from operative reiation to the wheel while the mandrel turns through an arc sufficient to bring the next succeeding chaser into proper position to be acted on. When this has been effected the mandrel is caused to approach and then recede from the wheel to effect a grinding action on the succeeding chaser. This action of the cam arm 87 is produced by means of a cam 100 journaled on a stud shaft 101 fixed to the rear wall of the casing 72,- the edge of this camengaging a follower plate 102 carried by the arm 87. The cam 100 hasfixed to or integral therewith a pinion 103 with which meshes a gear 104 carried by the sleeve 71 and whichis shown as retained thereon by means of a nut 105 threaded on the reduced extremity of the sleeve. The cam 100 is formed with a radial high portion 106 for the greater portion of its circumference but it also has a low port'on 107. While the high portion 106 is acting on the arm 87 the mandrel is held in its retracted position. When the low portion 107 is in position to be contacted w th this arm the mandrelis moved under spring pressure to present the chaserto the grinding wheel. This spring pressure is produced by means of a spring 108 bearing over. guide pins 109 and 110, the guide pin 109 projecting from the arm 87 and the pin 110 projecting from a r m portion 111 of the casing 72.

An adjustment for the position of the pivot 86 on which the cam arm 87 turns is also provided, this being accomplished by a pair-of v set screws 112 threaded through the rim 111 of the casing 72 andbearing 1n spaced relation on the edge of the pivot plate 85.

the lead of the chaser threads.

In time with the rotation of the chaser-carrying mandrel, the carriage is traversed in order to cause the driving wheel to follow This-is accomplished by means of the cam drum 7 0 before noted, which in addition to carrying the cams for performing various other func tions not material to this invention, carries a cam disk 115 against the edge of which rides j ustable stop screw to limit the motion of the" carriage under the action of the spring 118.

The mandrel having been supplied with two sets of chasers in the manner above described is inserted between the spindles 27 and and is adjusted so that it is nearly in contact with the grinding wheel. After the machine has been started, as each chaser is presented in proper relation to the grinding wheel, it is moved thereagainst to form a concave thread out therein and then retracted, the several chasers being acted on successive ly as the mandrel rotates. The mandrel is also traversed so that the threads "of each chaser are presented in succession to the grinding wheel. z

From the foregoing description of certain embodiments of this invention it should be evident to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of this invention as defined by the appended claims. 40

I claim:

1. A machine of the class described comprising a grinding wheel, a carriage, means onsaid carriage for rotatably supporting a mandrel constructed to support a plurality of chasers having their work engaging faces presented outwardly from the axis of rotation of said mandrel, means for rotating said mandrel to present said chasers successively toward said wheel, and means acting to effect approach between said wheel and mandrel whenever a chaser is presented toward said wheel to cause said wheel to grind said face, and then to effect a'retraction between said wheel and mandrel after a time of grinding so short relative to the speed of rotation of said mandrel that the face of each chaser is ground concave circumferentially relative tosaid mandrel. v

2. A machine of the class described comprising a grinding wheel, a carriage, means on said carriage for supporting a' mandrel constructed to support a plurality of chasers with their work engaging faces directed outwardly from the axisof said mandrel, means bring said chasers successively into operative angular relatlon relatlve to said wheel, and -means to move said mandrel and wheel one relatively from and toward the other when a chaser is so presented to cause said wheel.

to act on a chaser and while said mandrel is substantially stationary angularly.

3. A machine of the class described com prising a grinding wheel, a carriage for supporting work in operative relation to said wheel, spindles carried by said carriage for supporting the work, means for rotating the work, and means for moving one of said spindles quickly both toward and from the wheel at certain angular positions thereof to effect the cutting action of the wheel during such a short period of time that the work is substantially stationary angularly during each period.

4. In a machine of the class described comprising a grinding wheel, atraversing carriage, a headstock and a tailstock carried bysaid carriage for rotarily supporting work to be acted on by said wheel and to be traversed relative to said wheel by the traverse of said carriage a shaft journaled longitudinally of said carriage, a spindle in said headstock, a cooperating spindle in said tailstock, means for supporting the work therebetween, means for rotating the work by the rotation of said shaft, and means for effect-' ing a rapid motion of one of said spindles at certain angular positions of the work to move the work toward and then away from said wheel to effect a cutting action on the work only when it is substantially angularly stationary in definite angular positions.

5. A machine of the class described comprising a grinding wheel, a traversing car riage, a headstock and tailstock carried by said carriage, a shaft journaled longitudinally of said carriage, a spindle in said headstock, a cooperating spindle in said tailstock, means for rotating work carried by said spindles by rotation of said shaft, one of said spindles being pivoted between its ends, whereby its work-supporting end may be swung toward and from said; wheel, and means for effecting a quick motion of said spindleend toward and then, from the wheel at definite angular positions ofthe work.

6. A machine of the class described comprising a grinding wheel, a traversing carriage, a headstock and a tailstock carried by said carriage, a shaft journaled longitudi; nally of said carriage, a spindle in said headstock, a cooperating spindle in said tailstock,

-ends, whereby its work-supporting'end may be swung toward and from'said wheel, and a cam operated in time with the rotation of forrotating said mandrel about said axis to the work for effecting such swinging motion of said spindle toward and from the work at definite angular positions of the work.

- 7-. A machine of the class described comprising a riage, a headstockand a tailstock carriedby said carriage, a shaft journaled longitudinally of said carriage, a spindle in said headstock, a cooperating spindle in said tailstock, means for rotating work supported by said spindles from the rotation of said shaft,

' one of said spindles being pivoted between its ends, whereby its work-supporting end may be swung toward and from said wheel, a cam'opera'ted in time with the rotation of the work for effecting motion of said spindle toward and from the wheel at definite mandrel adjacent the edge of a grinding angular positions of the work, and means for adjusting the action of said cam.

8. A machine of the class described comprising a grinding wheel, means to rotatably support work, and m'eans to effect awheel, and as each chaser comes into definite angular position relative to said wheel moving the mandrel quickly theretoward and then retracting it to effect a concave cut on the outwardly presented chaser face circumferentially of the mandrel while the mandrel is substantially stationary angularly.

11. A mandrel having a disk portion provided with a plurality of recesses each adapted to receive a chaser having its threads outwardly presented, and means for fixing the chasers in position, said recesses being inclined slightly to the axis of the mandrel to present the threads in planes corresponding to the helix angle of threads of the working diameter of the several chasers.

12. A mandrel having a disk portion provided with a plurality of recesses substantially axially of the mandrel, said recesses being of difi'erent depths to bring the threads of corresponding chasers of a plurality of sets 'adjacently arranged in said grinding wheel, a traversing car-' bring the threads of corresponding chasers .of a pair of sets adjacently arranged 1n said recesses into registry with the same pitch line.

' 14. A mandrel having a disk portion provided with a plurality of recesses each adapted to receive a chaser having its threads outwardly presented, and means for fixing the chasers in position, said recesses being inclined slightly to the axis of the mandrel to present the threads in planes correspondingto the pitch angle of threads of the working diameter of the several chasers, said, recesses being alternately of difierent depths to bring the threads of corresponding chasers of a pair of sets adjacently arranged in said recesses into registry with the same pitch line.

15. A machine of the class described comprising a grinding wheel, a carriage, means on said carriage for rotatably supporting a mandrel constructed to support a chaser having its work-engaging face outwardly extending from the axis of rotation of said mandrel in operative relation to said wheel,

means for rotating said mandrel, and means acting to effect an approach and then a recession between said wheel and said mandrel to present said chaser during such a small period of time relative to the speed of rotation of said mandrel that said wheel grinds the face of said chaser concave circumferentially relative to said vmandrel.

In testimony whereof I have afiixed my signature.

RALPH E. FLANDERS.

recesses into registry with the same pitch line. r

13. A mandrel having a disk portion prodad with a plurality of r substan- 

